Tubing hanger running tool and subsea test tree control system

ABSTRACT

A system for providing power to elements down-hole in a subsea well includes a control pod having at least one shuttle valve, a down-hole hydraulically-actuated device having at least one internal porting mechanism in fluid communication with the at least one shuttle valve, a blowout preventer stack connected to the down-hole device, the blowout preventer stack including a first ram and a second ram, and a choke line in fluid communication with an area between the first ram and the second ram. The at least one shuttle valve controls distribution of hydraulic pressure applied through the choke line to the internal porting mechanism for selective distribution of power to the hydraulically-actuated device.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.60/558,078, entitled, “Subsea Test Tree,” filed Mar. 30, 2004, and toU.S. Provisional Application No. 60/580,474, entitled, “Tools forCompleting Subsea Wells,” filed Jun. 17, 2004, each of which is hereinincorporated by reference.

FIELD OF THE INVENTION

This invention relates to subsea well technology, and specifically to animproved tubing hanger running tool and subsea test tree control systemand method of controlling hydraulic/electric tools or equipment usedduring drilling, testing or completion of a subsea well.

BACKGROUND OF THE INVENTION

A subsea well constructed for producing hydrocarbons consists of aseries of concentric drilled and cased bores. The casings typicallyinclude sections of threaded and coupled pipes screwed together. Thecasings are run into the well bore, suspended (landed) in a wellheadattached to the first casing string (referred to as conductor pipe), andcemented in place by circulating cement down the casing and up into theannular area between the casing and well bore.

In the process of drilling and equipping (completing) a subsea well, itis often necessary to suspend production tubing in the subsea wellheador christmas tree with a device known as a tubing hanger. The tubingtypically consists of sections of threaded and coupled steel pipessimilar to casing, but smaller in diameter and usually higher inpressure rating. Unlike casing, the tubing is not cemented in place andtherefore can be replaced. In addition to suspending the tubing in thewellhead or in a Christmas tree, the tubing hanger also seals off theannular space between the tubing and the production casing and providesaccess to down-hole devices such as safety valves, chemical injectionports, down-hole pressure gauges, as well as other devices.

In some drilling and completion procedures, a subsea well is connectedto a floating platform on the surface of the sea through a BlowoutPreventer Stack (BOP) and a marine drilling riser. For example, this isoften done in performing a Drill Stem Test or a flow test and cleanupfor a completed subsea well. During such procedures, a subsea test tree(SSTT) is landed in the wellhead, or subsea tree, for safety purposes.The SSTT is the primary safety device in containing well pressure in theevent that the floating drilling vessel is required to disconnect fromthe well in an emergency.

The process of running the SSTT is cumbersome and time consuming to thewell operator and requires the rental of expensive equipment (i.e.control panel, hydraulic power supply, control umbilical, hose reel,etc.). Along with the drilling rig time associated with rigging up andrunning the umbilical and strapping it to the work string, thisprocedure can add five hundred thousand dollars or more to the wellcost, depending on the water depth. The cost can include the rental costof the SSTT itself, the umbilical, and the control panel and hydraulicpower system, as well as the rig time to run the SSTT with theumbilical, strapping the umbilical to the tie back string and rigging upthe hydraulic control system.

SUMMARY OF THE INVENTION

In general, in an aspect, the invention provides a system for providingpower to elements down-hole in a subsea well. The system includes acontrol pod having at least one shuttle valve, a down-holehydraulically-actuated device having at least one internal portingmechanism in fluid communication with the at least one shuttle valve, ablowout preventer stack connected to the down-hole device, the blowoutpreventer stack including a first ram and a second ram, and a choke linein fluid communication with an area between the first ram and the secondram. The at least one shuttle valve controls distribution of hydraulicpressure applied through the choke line to the internal portingmechanism for selective distribution of power to thehydraulically-actuated device.

Embodiments of the invention may include one or more of the followingfeatures. The shuttle valves may be battery activated shuttle valves.The system may include an acoustic signal generator. The shuttle valvesmay be controlled by an acoustic signal generated by the acoustic signalgenerator. The shuttle valves can be controlled with electronic signalsreceived by the control pod. The shuttle valves can be electricallycontrolled. The control pod may include a receiver to decode pressurepulses generated to control the shuttle valves. The down-holehydraulically actuated device may include a component in at least one ofa tubing hanger running tool, a subsea test tree, and a tubing hanger.The blowout preventer stack may include a port positioned between thefirst ram and the second ram. The choke line can be in fluidcommunication with the port. The system can include an electroniccontrol panel and a slip ring to provide control commands to the shuttlevalves in the control pod.

Additional aspects of the invention are directed to a method ofproviding hydraulic and electric power to tools in a subsea test treesystem, the system comprising a blowout preventer stack having a firstram and a second ram and a choke line through which hydraulic pressureis provided to a port in the blowout preventer stack. The methodincludes isolating an area between the first ram and the second ram ofthe blowout preventer, distributing hydraulic pressure through the chokeline to the area between the first ram and the second ram of the blowoutpreventer, and controlling the distribution of hydraulic pressurethrough the choke line to a hydraulically-actuated device by actuatingshuttle valves.

Embodiments of the invention may include one or more of the followingfeatures. The method may further comprise generating an acoustic signaland controlling the shuttle valves with the acoustic signal. The methodmay also comprise generating pressure pulses, receiving the pressurepulses in a control pod housing the shuttle valves, and decoding thepressure pulses to control the shuttle valves. The method may includeclosing the area between the first ram and the second ram above andbelow an inlet from the choke line and providing a seal for hydraulicfluid in the blowout preventer.

Various features of the invention may provide one or more of thefollowing capabilities. Using the sealing capabilities of the BOP andthe existing hydraulic power and control functions allows the user toavoid having to obtain the umbilical, the control unit and a hydraulicpower supply. Also, rig time is lessened due to the elimination of thenecessity of hooking up the aforementioned components, as well as thetime required to run the umbilical. Savings can be as much as one-halfof the standard cost of renting and running a known subsea test tree.Safety is enhanced by the elimination of the control umbilical requiredin the current SSTT designs.

Various features of the invention may provide one or more of thefollowing capabilities. In embodiments of the invention, the need for ahose reel, a control umbilical, a hydraulic control panel, a hydraulicpower supply and down-hole accumulator are substantially eliminated. Therig time associated with running the control umbilical is alsosubstantially eliminated. The efficiency of the drilling of a subseawell can be more cost effective and safer for the user.

These and other features of the invention will become more apparent fromthe following description in which reference is made to the appendeddrawings briefly described below.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the invention will become more apparent fromthe following description in which reference is made to the appendeddrawings briefly described below.

FIG. 1 is a schematic diagram of a floating drilling rig.

FIG. 2 is a schematic diagram of a Subsea Test Tree/Tubing HangerRunning Tool.

FIG. 3 is a schematic diagram of an alternative Subsea Test Tree/TubingHanger Running Tool.

FIG. 4 is a schematic diagram of a Subsea Test Tree/Tubing HangerRunning Tool having an electric power ram.

FIG. 4A is a magnified schematic diagram of the electric power ram ofFIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

The features and other details of the invention will now be moreparticularly described with reference to the accompanying drawings. Itwill be understood that particular embodiments described herein areshown by way of illustration and not as limitations of the invention.The principal features of this invention can be employed in variousembodiments without departing from the scope of the invention.

Embodiments of the invention are related to subsea well technology, andspecifically to an improved tubing hanger running tool (THRT) and subseatest tree (SSTT). Embodiments of the invention eliminate a controlumbilical and associated hydraulic power pack, as well as associatedreel and control panel. Embodiments of the invention use a choke and/orkill line of the blowout preventer system (BOP) to supply hydraulicpower. Further, embodiments of the invention use battery powered shuttlevalves to direct hydraulic fluid through internal piping and ports toperform many functions in a subsea system. Embodiments of the inventionsupply hydraulic power to the THRT and to the tubing hanger and SSTTthrough a blowout preventer that is generally employed in the drillingand completion (equipping for production) of a subsea well. Embodimentsand portions of the invention can be used for completing a subsea well,flow testing a subsea well, or for purposes other than completing ortesting. Other applications of the embodiments will be apparent to thoseskilled in the art.

In embodiments of the invention, hydraulic power is provided through aport in the side of the THRT, rather than through a control umbilical.The port is isolated between two pipe rams in the blowout preventer(BOP). Embodiments of the invention further provide closing the piperams such that hydraulic power can be supplied to the port through thechoke or kill line that is available on standard subsea blowoutpreventer stacks. Further, battery-powered shuttle valves are used todirect hydraulic fluid through internal piping to functions that requirethe hydraulic fluid. Shuttle valves are controlled in at least one of anumber of ways, including, but not limited to, by acoustic signals,electronic signals, pressure pulse telemetry, and electrically.

Referring to FIG. 1, a schematic of the general arrangement of afloating drilling operation and selected systems therein is shown. Asubsea well system 10 includes a floating drilling rig 12 positionedabove sea level, and a marine riser 14, a lower marine riser package 16and a BOP stack 18, all positioned below sea level. Subsea wells arebuilt by establishing a wellhead housing on a conductor casing pipe, andwith a blowout preventer stack 18 installed, drilling a well bore downto the producing formation and installing concentric casing strings,which are cemented at the lower ends and sealed with mechanical sealassemblies at each string's upper end. The lower marine riser 16 is asub-system of the blowout preventer stack 18, and allows the rig andriser system to be disconnected from the BOP stack in the event anemergency disconnect is required. The system depicted is aguide-lineless system. Other systems, including systems that utilizeguide lines, are known in the art.

In order to equip the cased well for production, a tubing string is runin through the BOP 18 and a tubing hanger is landed in the wellhead.Thereafter, the BOP stack 18 is removed and replaced by a tree havingone or more production bores extending vertically to respective lateralproduction fluid outlet ports in the wall of the tree. In an alternateembodiment, the tubing hanger may be landed in a subsea christmas treemounted on the wellhead. The tubing hanger is generally installed byusing a hydraulically activated tubing hanger running tool.

To equip the well for production, a tubing hanger running tool (THRT) 26and a subsea test tree (SSTT) 28 may be employed. Referring to FIG. 2,components that may be used with the THRT 26 and SSTT 28 include a hosereel 30, a hydraulic power pack 32, an electro-hydraulic control panel34, an electro-hydraulic control umbilical 36, a flow control head 38, aBOP control panel 40, a choke line 42, a BOP control umbilical 44, amarine riser 14, an accumulator 46 for the THRT and the SSTT, a controlpod 48 for the THRT and the SSTT, a retainer valve 50, a hydraulicdisconnect 52, a ball joint 54, an annular BOP 56, BOP pipe rams 58 anda tubing hanger 60. The tubing hanger 60 is connected to the THRT 26,the umbilical 36 is connected to the control pod 48, and the assembly isrun into the well through the drilling riser 16 and blowout preventerstack 18, which are attached to the wellhead. Alternatively, the BOP 56may be landed on the subsea christmas tree, and the tubing hanger may berun and landed in the subsea christmas tree. The THRT 26 and the SSTT 28can be run together or separately.

The THRT 26 provides several functions, including but not limited to:facilitating “soft landing” features of the tubing hanger; testing ofthe various tubing hanger seals; and actuating locking rings to lock thetubing hanger in place. These functions may be actuated by hydraulicpressure delivered to the THRT 26 from the surface vessel (e.g., thefloating production platform or drilling rig 12) through the controlumbilical 36 connected to the dedicated hydraulic power unit 32 on thesurface vessel 12, and operated with the hydraulic control panel 34.Generally, the control umbilical 36 system transfers high and lowpressure fluid supply, annulus fluids and electrical power/signals tothe BOP, subsea tree and other equipment down-hole.

The SSTT 28 has hydraulically actuated valves that are powered andcontrolled through the electro-hydraulic control line 36 running fromthe surface platform 12 to the SSTT 28. The system is run on a highpressure riser, or tie back string 63, run inside the marine riser 14and landed and sealed inside the wellhead or subsea tree. The controlumbilical 36 is strapped to the tieback string 63. A surface tree ishooked up to the tie back string to control the flow of the well andallow wireline lubricator access to the well for wireline work. The SSTT28 cuts the wireline, seals the well, and releases the tie back stringin the event that the platform is required to disconnect from the well,for example, in an emergency.

Referring to FIG. 3, the electro-hydraulic control panel 34, power pack32, hose reel 30 and electro-hydraulic umbilical 36 of the system ofFIG. 2 can be replaced by an electronic control panel 61 and a slip ring62 around the running string 64. The system of FIG. 3 operates without adown-hole accumulator. The system includes the retainer valve 50, thehydraulic disconnect 52, the control pod 48, the pipe rams 58, the SSTT28 and the THRT 26. The electronic control panel 61 and the slip ring 62provide the control commands (e.g., electronically, electrically,acoustically, etc.) to the battery operated shuttle valves in thecontrol pod 48. The shuttle valves direct/control hydraulic power fluidto the various functions of the THRT 26, the tubing hanger 60 and theSSTT 28.

The hydraulic power in the system of FIG. 3 is provided via a choke/killline 42. The control pod 48 includes a series of shuttle valves 68. Theseries of shuttle valves 68 in the control pod 48 for the THRT/SSTT aremanifolded to hydraulic power supplied through internal porting in theTHRT 26 and the SSTT 28. The hydraulic power is supplied through thechoke or kill line 42 via a port in the THRT 26. The port is spacedbetween the lower two pipe rams 58 in the BOP stack 18. For example, therams 58 are closed, which isolates the port so the port can receivehydraulic power from the choke/kill line 42. The choke or kill line 42is generally approximately 3 inches in diameter; however, otherdimensions are possible and envisioned. The hydraulic power can havesufficient capacity/volume so as to substantially eliminate the need fora down-hole accumulator.

Control of the hydraulic power fluid to the various functions to beoperated is through the internal manifold and shuttle valves 68 in thecontrol pod 48. The lower pipe rams 58 are closed above and below theinlet from the kill line to provide a seal for the hydraulic power fluidto enter a port in the THRT 26. The port is connected to the internalmanifold and shuttle valves.

When actuated, the shuttle valves 68 direct hydraulic power to thevarious functions in the tubing hanger/THRT/SSTT. These functionsinclude, but are not limited to, soft landing, seal testing, and atubing hanger lockdown function.

A hydraulic passage can be made from the THRT 26, through the tubinghanger and, by using galley seals, is connected with a passagewaythrough the subsea christmas tree. On the outside of the tree anadditional manifold of shuttle valves 68 distributes the hydraulic powerto the various hydraulically activated tree functions (valves,connectors, test ports, etc.) The shuttle valves 68 may be batteryactivated and controlled, as described below. In this way, the tree canbe functioned/operated without the need for a separate electricalumbilical.

The shuttle valves 68 in the control pod 48 are battery operated, forexample. Battery power to the shuttle valves 68 can be controlled in anumber of ways, now discussed for simplicity in terms of shuttle valvecontrols. The battery pack for the shuttle valves 68 may be controlledby acoustic signal through the water (or work string). The signal ispicked up and decoded by a receiver in the control pod 48 and theshuttle valves are then actuated by electric impulse from the decoder.Electric power is provided by a battery pack in the control pod for theSSTT 28 and the THRT 26.

Referring to FIGS. 4 and 4A, a separate set of rams 58 in the BOP stack18 can be used to provide electric power to the control pod 48. The BOPincludes the rams 58, 59, a power sub 72 having insulation 74 and splitlines 76 that provide electrical power from the BOP control umbilical44. The opposing rams 58, 59 include electrodes 70 horizontally opposedbut offset in the vertical plane. Electric power is supplied from thecontrol umbilical 44 for the BOP stack 18. The configuration shown inFIG. 4A is non-orienting and transmits electric power through anodes inthe ram body to the power sub in the running string. The annulus in theBOP stack 18 is filled with a non-conductive fluid circulated into placethrough the choke or kill line. Pressure on the rams 58, 59 as theyclose around the power sub squeezes out the non-conductive fluid andmakes the electrical connection. An orienting device can be used in thewellhead and BOP stack 18. Wet mate-able electrical connectors can beused in the rams 58 and the power sub.

In alternatives of the embodiments described herein, the principleapplied to the control pod, THRT and SSTT can also be applied to achristmas tree running tool. In the case of a christmas tree runningtool, the hydraulic power may be supplied through the treerunning/landing string. The tree running tool (CTRT) is hydraulicallylocked to the tree, and hydraulic passages connect from a manifold inthe CTRT, through the tree to another manifold external to the tree,thence to the various tree functions. Hydraulic power through bothhydraulic manifolds may be controlled by battery operated shuttlevalves. The shuttle valves are controlled according to at least one ofthe various methods discussed above.

In embodiments of the invention, the battery operated shuttle valves arecontrolled by acoustic signals and acoustic decoder. Alternatively, theshuttle valves 68 are controlled by pressure pulse telemetry as is usedin “logging while drilling” (LWD) tools. The coded series of pressurepulses is generated on the surface and decoded by a receiver in thecontrol pod 48. The receiver directs electric power, from a battery packin the control pod 48, to the shuttle valves 68. A further alternativemethod by which to control the shuttle valves 68 is by a special landingstring containing an electric conductor embedded in or attached to thewall of the pipe. In this method the electric power is supplied directlyto the shuttle valves 68 through a multiplexing system similar to amultiplex system for controlling production from subsea wells. A stillfurther alternative includes controlling the shuttle valves by use of alanding string employing an electronic signal transmission wire attachedto or embedded in the pipe to control battery powered shuttle valves 68in the control pod 48. For example, Grant Prideco's product Intellipipe™can be used to provide an electronic signal transmission. Any othermethod of delivering a signal to a battery pack power supply in order toactivate the shuttle valves 68 without the use of an umbilicalconnection to the down-hole tools is possible and envisioned.

From the foregoing detailed description it has been shown how theobjects of the invention have been obtained in a preferred manner.However, modifications and equivalence of the disclosed concepts such asthose which would occur to one of ordinary skill in the art are intendedto be included within the scope of the present invention. Suchequivalents are considered to be within the scope of the presentinvention.

Various substitutions, alterations, and modifications may be made to theinvention without departing from the spirit and scope of the inventionas defined by the claims. Other aspects, advantages, and modificationsare within the scope of the invention. The contents of all references,issued patents, and published patent applications cited throughout thisapplication are hereby incorporated by reference. The appropriatecomponents, processes, and methods of those patents, applications andother documents may be selected for the present invention andembodiments thereof.

1. A system for providing power to elements down-hole in a subsea well,the system comprising: a control pod having at least one shuttle valve;a down-hole hydraulically-actuated device having at least one internalporting mechanism in fluid communication with the at least one shuttlevalve; a blowout preventer stack connected to the down-hole device, theblowout preventer stack including a first ram and a second ram; a chokeline in fluid communication with an area between the first ram and thesecond ram, wherein the at least one shuttle valve controls distributionof hydraulic pressure applied through the choke line to the internalporting mechanism for selective distribution of power to thehydraulically-actuated device.
 2. The system of claim 1, wherein theshuttle valves are battery activated shuttle valves.
 3. The system ofclaim 1, further comprising an acoustic signal generator, wherein theshuttle valves are controlled by an acoustic signal generated by theacoustic signal generator.
 4. The system of claim 1, wherein the shuttlevalves are controlled with electronic signals received by the controlpod.
 5. The system of claim 1, wherein the shuttle valves areelectrically controlled.
 6. The system of claim 1, wherein the controlpod includes a receiver to decode pressure pulses generated to controlthe shuttle valves.
 7. The system of claim 1 wherein the down-holehydraulically actuated device includes a component in at least one of atubing hanger running tool, a subsea test tree, and a tubing hanger. 8.The system of claim 1 wherein the blowout preventer stack includes aport positioned between the first ram and the second ram, and whereinthe choke line is in fluid communication with the port.
 9. The system ofclaim 1 further comprising an electronic control panel and a slip ringto provide control commands to the shuttle valves in the control pod.10. A method of providing hydraulic power to tools in a subsea wellsystem, the system comprising a blowout preventer stack having a firstram and a second ram and a choke line through which hydraulic pressureis provided to a port in the blowout preventer stack, the methodcomprising: isolating an area between the first ram and the second ramof the blowout preventer; distributing hydraulic pressure through thechoke line to the area between the first ram and the second ram of theblowout preventer; and controlling the distribution of hydraulicpressure through the choke line to a hydraulically-actuated device inthe subsea well by actuating shuttle valves positioned in a control pod.11. The method of claim 10 further comprising generating an acousticsignal and controlling the shuttle valves with the acoustic signal. 12.The method of claim 10 further comprising: generating pressure pulses;receiving the pressure pulses in a control pod housing the shuttlevalves; and decoding the pressure pulses to control the shuttle valves.13. The method of claim 10 further comprising closing the area betweenthe first ram and the second ram above and below an inlet from the chokeline and providing a seal for hydraulic fluid in the blowout preventer.